661626593 has 2 divisors, whose sum is σ = 661626594. Its totient is φ = 661626592.

The previous prime is 661626551. The next prime is 661626601. The reversal of 661626593 is 395626166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 627602704 + 34023889 = 25052^2 + 5833^2 .

It is a cyclic number.

It is not a de Polignac number, because 661626593 - 2¹⁸ = 661364449 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (661629593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330813296 + 330813297.

It is an arithmetic number, because the mean of its divisors is an integer number (330813297).

Almost surely, 2^661626593 is an apocalyptic number.

It is an amenable number.

661626593 is a deficient number, since it is larger than the sum of its proper divisors (1).

661626593 is an equidigital number, since it uses as much as digits as its factorization.

661626593 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 349920, while the sum is 44.

The square root of 661626593 is about 25722.1031993887. The cubic root of 661626593 is about 871.3734386218.

The spelling of 661626593 in words is "six hundred sixty-one million, six hundred twenty-six thousand, five hundred ninety-three".